Screw-cutting die.



A. J. FRANCE.

SCREW CUTTING DIE.

APPLICATION FILED JULY 12. I916.

Patented Feb. 5, 1918.

IN V EN TOR.

MEET d. FRANCE, 01E DETROIT, MICHIGAN, ASSIGl-NOR T0 MURCHET MACHINETUUL CUTWANT, 0F JDEHLRUTT, MICHIGAN, h

CORPORATION OF MICHIGAN.

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hpeeltlcatton of Letters Patent.

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hpplteatlon filed July 12, laid. aerial Ito. water.

To all whom it may concern Be it known that l, ALBERT J. Frauen, a,

citizen of the United States, residin at Detroit, in the county of Wayneand tate of Michigan, have invented new and useful Improvements inScrew-Cutting Dies, of which the following is a specification.

This invention relates to screw-cutting dies, and more particularly tothat class thereof, in which the thread-cutting devices or chasers areautomatically released from the work at a predetermined point of theoperation. 7

The invention has for one of its objects the provision of an instrumentof the kind named comprising a rotatable beveled adjusting collarcoiiperative with the chasers for precisionizing their positiondiametrically of the work. furthermore, for its object the improvedconstruction of the slidabl'e chaser-carrying head which is movedforward by the chasers cutting their way into the workeven after theshank of the instrument has been stopped against advancing, thiscontinued advance of the head allowing the chasers to suddenly freethemselves from the tvork. Further objects of this invention willhereihafter appear and be particularly defined in the claims.

The invention has been clearly illustrated in the accompanying drawings,in which similar characters denote similar parts, and in which- Figure lis a front view of my improved device.

Fig. 2 is a side view of the same.

Fig. 3 represents a longitudinal section on line 3-3 of Fig. f.

Fig. 4 shows a fragmentary outside view of the slidable head, lookingthe direction of arrow 4 of Fig. 3.

Fig. 5 is a longitudinal section on line 5-5 of Fig. 1. illustrating theparts in closed-in. position.

F Fig. 6 is a front view taken on line 6 of -Fig. l is a cross-sectipnon line 'l-t' of Fig. 5, and Fig. 8 illustrates the outer shell, lookingin the direction of arrow 8 of Fig. l. 4

Referring to the drawings, 10 denotes the shank portion of the deviceadapted to be secured in the turret of a lathe and having a flange itand carrying a head 13 provided movement relatively to the shank,

The invention has,

with a pair of driving pins 12 for holding the main bod againstrotation, without however inter ering with any longitudinal the pinsentering suitable recesses 14: in the body (see Figs. 3 and 7). Thefront face of the flange d1sk 11 has also a steady-stud 15 formaintaining the head 13 and the shank in central relation with eachother, said stud entering a central longitudinal aperture 16' in thehead.

The head 13 carries in its front face a plurality of progressively-cutchasers or threading tools 17 adapted for radial adjusting movement,each chaser having a'. backing face 17 (see Fig. 3) which engages, whenin cutting position (see Fig. 5) the inner face of a hardened wearingblock 18, all the several blocks being thus surrounded and engagedattheir outer faces by an annulus 19. The front faces of the severalchasers and thehead 13.

are flush, the chasers being set into slots (see Fig. 6) so that a coverplate 20, screwed to the head by screws 21, will hold these partstogether Each chaser is normally pushed outward against its wearingblock18 by: one end of a lever 22 lying Within a longitudinal slot 23provided therefor in the head, and having its pivot 24 so disposed as toestablish on said lever a tail-portion 22, which, when the front end ofthe lever is pushed outward by a spring 25 carried by the head, willserve to limit the outward movement of the lever. By referring to Fig. 5it will be seen that the vchaser has an aperture 26 to receive thelever-end.

The several wearing-blocks are seated in suitable cut-out portions 27!(see Fig. 2) provided in the front end of a shell 23 which incloses theseveral parts thus far mentioned excepting the blocks which are free tobe moved radially within the cuts 27 but are held against frontwiselongitudinal movement-by virtue of lips 29, as shown.

The several wearing blocks 18 may be positively moved radially inwardlyor be permitted to move outwardly, as desired, for the purpose ofprecisionizing the opening between the chasers in conformity with acertain diameter of thread to be but. For this reason each block has acone-face or bevel 18*, all of these faces being engaged llltl by thecorrespondin ly-shaped inner face of the annulus 19 a ove referred to,this annulus having a screw-threaded connection with the shell 28 sothat it may be rotated thereon to move longitudinally and thus move theblocks toward or away from each other, according to the direction ofrotation.

In order to preserve the radial alinement between each chaser and itswearing block, she shell 28 and head 13 are keyed together bypin-and-slot construction 30 (see Fig. 8).

It will now be seen that, when the several parts are in their closed-inpositions shown in Fig. 5, and the annulus 19 is therr rotated by handso as to move the same forward on the shell '28, the several chaserswill be moved outwardly, due to the cooperative bevel faces of theannulus and wearing blocks. A rotation of the annulus causing a movementtoward the rear of the head will cause the chasers to be moved towardeach other. The amount of such radial or inward adjusting movement maybe read on the front face of the device, the annulus having a series ofgraduations to be read in conjunction with an index pointed i on thestationary cover plate (see Fig. 1). The linear pitch of the screwthread and the bevel of the wearing blocks are preferably soproportioned that a rotation of the annulus for an amount equal to onegraduation-division will move the chagers radially for one-thousandth ofan mc The device, when in use, is secured with its shank in the turretof a lathe. The rod to be screwthreaded is clamped into the spindle ofthe lathe head, and the turret slide is then moved toward the lathe headuntil the chasers have commenced to cut. After that the advance movementof the turret slide depends upon speed with which the screwthreads arecut, as usual in machines of this class. As soon as the advance movementof the turret, slide is stopped, either by stop member on the lathe-bedor otherwise, the continued screw-cutting operation on the Work willstill continue to advance the chasers and with them the head 13 of thedevice, until this continued advance movement has proceeded far enoughto bring the backing-faces 17 of the chasers from underneath thewearing-blocks 18. By referring to Figs. 3 and 5 it willbe noted thateach chaser has a beveled drop-off face 17", so that, as soon as thefront edge of said beveled face has passed beyond the front edge of itswearing block, the spring 25 and lever 22 can then become effective inopening the chaser and thus quickly release it from the work, it beingself evident that this outward movement of the chasers will also resultin moving the several wearing-blocks, together with their carrying shell28 and the annulus 19 slightly rearward relatively to the chasers.

The length ofthe cutting operations can therefore be accurately gaged.

Means are also provided for opening or closing the chasers by hand,these means consisting preferably of a hand lever 35 passing through anaperture 36' in the shell 28 and having its lower end secured in atilting block 37 which is pivotally seated, as at 38, within a recess 39of the head-member 28. It will be readily understood that by throwingthe lever 35 from right to left, in Fig. 3, the head and shell willassume the positions shown in Fig. 5, in which the chasers areclosed-in, ready to work.

I claim:

1. A screw-cutting die comprising a head, chasers carried thereby, eachchaser having an aperture, and means for precisionizing the positions ofsaid chasers radially, said means consisting of a shell surrounding saidhead, an annulus carried by said shell and having an inner beveled face,and means for moving said annulus on the shell longitudinally, andspring-actuated levers pivoted in the head and having their front endsdisposed within said chaser apertures, for opening the chasers at apredetermined point of the advance movement of the head relatively tothe shell.

2. A screw-cutting die comprising a head, chasers carried thereby, andmeans for precisionizing the positions of said chasers radially, saidmeans consisting of a shell surrounding said head, an annulus carried bysaid shell and having an inner beveled face, and means for moving saidannulus on the shell longitudinally, and independent springactuatedlevers pivoted in the head and removably engaging said chasers, foropening the chasersby the advance movement of the head relatively to theshell, and means for limiting the outward movement of said levers tomaintain said chasers in the head subsequently to their clearing theshell.

3. A screw-cutting die comprising a head, chasers carried by said headand each having a recess in its rear face, and means for precisionizingthe position of said chasers radially, said means consisting of a shellsurrounding said head, an annulus carried by the shell and having aninner beveled face, spring-actuated levers pivoted in the head andhaving tail pieces for limiting the outward movement of said levers, theforward ends of said levers entering said recesses of the chasers,respectively.

4. A screw-cutting die comprising a shell having cut-out portions in itsfront end, wearing blocks radially movable in said cutout portions andeach having an outer beveled face, means for locking said blocks againstlongitudinal movement in the shell, 9. head slidable in the shell, meansfor locking said shell and head against rotation relatively to eachother, chasers carried by lid naaaaaa said head and radially movabletherein, an annulus carried by said shell and having an inner beveledface cooperative with-the beveled outer faces of the wearing blocksrespectively, and means for moving said annulus on the shelllongitudinally.

5. A screw-cutting die comprising a shell, wearing blocks radiallymovable therein, and each having an outer beveled. face, a head slidablewithin said shell, chasers radially movable in said head and each havinga backing face engaging said wearing blocks, an annulus earned by saidshell and having an inner beveled face cooperative with the beveledouter faces of said wearing blocks, said annulus being in screw-threadedengage'ment with said shell for moving the same longitudinally thereon.

6. A screw-cutting die comprising a head,

tilt

chasers carried thereby and movable radially therein, each chaser havinga drop-off face, a shell surrounding said head and having 5 o a .1n 1tssurrounding wall an aperture, an annulus carried by and movable on saidshell for variably limiting the outward movement of said chasers, blockscarried by said shell and holding said chasers in closed-in posi; tions,a tiltable lever pivotally seated in the head and passing through saidaperture for moving said head relatively to the shell to open or closethe chasers.

In witness whereof I hereunto subscribe my name in the presence of twowitnesses. ALBERT J. FRANCE.

Witnesses:

CHAS. 1B. Scmvnmr, V. L. ALLEN.

